Dramatic progress has been made in the fields of cell and developmental biology in recent years, largely due to the application of new technical approaches to classical problems. This has led to the need for advanced courses to train investigators to study those animal models, such as Xenopus, that have been important in making new discoveries. Funds are being sought to continue the Cold Spring Harbor Laboratory course on "Cell and Developmental Biology of Xenopus" which has been taught for eleven years as part of an integrated set of courses in a number of areas of modern biology. This course provides extensive laboratory exposure to the biology and manipulation of embryos from the frogs Xenopus laevis and Xenopus tropicalis. Xenopus is a vertebrate uniquely suited for studies of early development, since large numbers of embryos, from fertilization onward, can readily be obtained. Development is rapid and the large size of the embryos facilitates their micromanipulation. This allows analysis (at the single cell level if necessary) of such important issues as maternal regulation and embryonic inductions that are not feasible in mammalian, avian, or fish embryos. The course is suited both for those who have a knowledge of molecular biology and developmental biology but have had no experience with Xenopus, as well as those with some Xenopus experience who wish to learn newly developed, advanced techniques. The specific areas that will be covered are (1) Care and handling of Xenopus adults, removal of oocytes, induction of ovulation, egg collection, testis isolation, and in vitro and natural fertilization; (2) Stages of embryonic development and anatomy; (3) Whole mount in situ hybridization and immunohistochemistry, including double probe staining; (4) Microinjection of eggs and oocytes with lineage tracers, antisense morpholino oligonucleotides, mRNA, and DNA constructions; (5) Micromanipulation of embryos, including induction and transplantation assays; (6) Oligonucleotide antisense techniques for "knock-out" of maternal molecules; (7) Preparation and use of cell cycle extracts for construction of transgenic embryos; and (8) Use of Xenopus tropicalis as a genetic model. It is anticipated that the basic organization of the course and much of the course material will remain unchanged during the proposed period of support. However, fast-developing topics, such as the in vivo use of siRNA for gene knock-downs, new promoter sequences for use in transgenesis, and the availability of transgenic and mutant lines, will be discussed and integrated into the course as the field progresses.